1, Field of the Invention
The present invention relates to a magnetic bubble device.
The magnetic bubble device of the invention utilizes a cylindrical magnetic domain, or magnetic bubble, which is produced by a biasing magnetic field in a magnetic thin film or magnetic bubble chip, having single axis magnetic anisotropy. A magnetic bubble chip is a known component comprising amorphous magnetic thin films, or orthoferrite single crystals, or garnet single crystals formed into thin plate or film configuration.
2. Description of the Prior Art
In the prior art, orthoferrite or garnet single crystals having single axis magnetic anisotropy, are formed in the shape of a thin film, so that an easily magnetizable axis becomes perpendicular to the surface. A magnetic domain of cylindrical configuration, or magnetic bubble, is produced by applying a biasing magnetic field perpendicular to the magnetic bubble chip, perpendicular to the easily magnetizable axis, of a thin cut magnetic film, or of an amorphous magnetic thin film having single axis magnetic anisotropy and having an easily magnetizable axis perpendicular to the plane of the film. The magnetic bubble may be made to move by providing a magnetic field gradient. This is described in detail in a thesis entitled "Domain Behaviour in Some Transparent Magnetic Oxides" by R. C. Sherwood, J. P. Remeika and H. J. Williams, Journal of Applied Physics, Vol. 30, 1959, pages 215 to 225, and in a thesis entitled "Properties and Device Application of Magnetic Domain in Orthoferrites" by A. H. Bobeck, Bell System Technical Journal, Vol. 46, pages 1901 to 1925.
It is possible to construct different units such as, for example, logical arithmetic units, memory units, and the like by utilizing the characteristics of a magentic bubble and by matching two value data with the present and absent state of a magnetic bubble, and furthermore by combining different functions like magnetic bubble production, transfer, erasure, sorting, etc.
There are several know conventional methods of controlling a magnetic bubble. However, the most widely known method is by installing different types of Permalloy patterns on the surface of a magnetic bubble chip or by applying a rotating magnetic field parallel to such surface of such chip, as described in U.S. Pat. Nos. 3,534,347 and 3,543,252. This method consists of sucking the magnetic bubble in towards the magnetic pole produced at the Permalloy pattern. The Permalloy pattern is, for example, of T-type or I-type, and is formed over the magnetic bubble chip. The sucking operation is accomplished by applying a rotating magnetic field parallel to the magnetic bubble chip surface from outside. The rotating magnetic field is produced by supplying sine wave and cosine wave currents to two orthogonal solenoid coils. The magnetic bubble chip is positioned inside the two solenoid coils. The magnetic field rotates in a circular orbit. The magnetic bubble chip of this conventional type of magnetic bubble unit is placed inside orthogonal solenoid coils or Helmholtz coils, and current is passed through these coils. The current flow produces a magnetic field which is used as a rotating magnetic field.
However, the production of a magnetic field by the use of coils raises the surrounding temperature of the magnetic bubble chip. The rise in temperature consequently largely affects the magnetic characteristics of the magnetic bubble chip and creates the danger of breakdown in the different controls of the magnetic bubble such as, for example, its production, transfer, sorting, etc. This results in the destruction of the magnetic bubble and an increased possibility of loss of data. Suitable temperature design is thus an important problem.
Furthermore, since the magnetic bubble chip is enclosed by solenoid coils, the area for drawing out input and output leads becomes small. If an attempt is made to provide sufficiently large area, the coils become larger than essential, thus requiring a greater area for parts of the coils other than the orthogonal parts. If the size of the device is enlarged, several disadvantages such as, troublesome assembly work, etc., arise for locating the magnetic bubble chip inside the solenoid coil winding.
The principal object of the invention is to provide a magnetic bubble device with good heat radiation characteristics.
An object of the invention is to provide a magnetic bubble device having a sufficient area for drawing out input and output leads from the magnetic bubble chip of said device.
Another object of the invention is to provide a magnetic bubble device having a structure which simplifies its assembly in mass production.
Still another object of the invention is to provide a magnetic bubble device of simple structure, which is readily adaptable to include devices for discharging generated heat.
Yet another object of the invention is to provide a magnetic bubble device in which the magnetic bubble chip is not inside the winding of the drive coil.
Another object of the invention is to provide a magnetic bubble device of simple structure, which is inexpensive in manufacture, and functions efficiently, effectively and reliably to control the magnetic bubble produced thereby.